A study is proposed to determine the utility of various histological grading classifications in the estimation of survival in patients with cancer of the prostate. Four such classifications will be applied to prostatic cancer tissue by four pathologists and the results tested against patient survival. The population under study in this retrospective analysis will consist of 1,000 patients with cancer of the prostate cared for at the Mayo Clinic during the years 1958 to 1966. In addition to the pathologic data, information concerning the clinical status of the patients will also be included in the data bases to determine if its inclusion will increase the precision of survival estimates.